They asked the women to fill out a questionnaire about their use of non-vitamin, non-mineral specialty supplements, and then followed their progress for an average of six years.

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Study Finds Fish Oil May Reduce Breast Cancer Risk

They found that women who regularly used fish oil supplements had a 32 percent reduced risk of developing the most common form of breast cancer. Of the total number of women in the study, 880 developed the disease.

Findings Could Have Huge Impact

While acknowledging that the results were preliminary, she said they could have a huge impact.

Harvard University is conducting a randomized controlled trial of vitamin D and fish oils in older men and women, news that, she said, indicated there was enough evidence from the study to invest in additional research.

The downside of fish oil use in general seems limited to a slightly increased risk of bleeding, especially when combined with certain medications such as Coumadin and NSAID's, she noted.

Long-chain, omega-3 fatty acids (abundant in fish oil supplements and fatty fish) are essential building blocks for the cell membranes of the body and brain, blocking inflammation and allowing messages to be transmitted between cells, she said. Because the body doesn't produce it on its own, people must get it from their diet, and fatty fish is the best source.

Among those fish are salmon and sardines. There are plant-based sources of omega-3 fatty acids -- including canola, soybean and flaxseed oil -- but the body can't convert them to the more potent form as well as it can the ones that are found in fish, she noted.

For people who don't get 2 or more servings of fish a week, fish oil supplements are a great alternative for people at risk for heart disease, she added. People can take about 1 gram per day, either in liquid or capsule form. It is too soon to recommend fish oils solely to prevent breast cancer, however.

Fish oil and omega-3 fatty acids have already been proven to lower the risk of death and heart attack in people with have heart disease. Fish oil is also used to treat people with high levels of the blood fat known as triglyceride, and has been shown to have a beneficial effect on the healthy HDL cholesterol levels.

Omega-3 Helpful in Other Ways

The American Heart Association already says that omega-3 fatty acids are helpful to heart disease patients, while research has shown that omega-3 fatty acids decrease the risk of arrhythmia, a condition of abnormal heartbeats that can lead to sudden death.

Research is underway to determine the effects of omega-3 fatty acids on mental health and brain conditions, as well as prostate cancer.

The Fred Hutchinson Cancer Center study was part of a larger 10-year study that is looking at the effects of fish oil and other non-vitamin supplements on cancer in men and women.

Web-Extra Tips

There is a wide variety of fish oil supplements on the market. When shopping for omega-3 fish oil supplements, look for:

Quality. Make sure the supplement you purchase is of high purity.

Make sure it has the USP label, meaning that it's a supplement that has been verified by United States Pharmacopeia. USP is the non–governmental, official public standards–setting authority for prescription and over–the–counter medicines and other healthcare products that are manufactured or sold in the United States.

Consider that big-box store brands are often as good as name brands.

Many fish oil products are advertised on the Internet. They're not regulated by the U.S. Food and Drug Administration, so if you don't know which ones to choose, ask your doctor for a recommendation.